My Bad on the html. The long dimension is just over 5 ft.


"AP" wrote in message
...
I dissagree with your specs. The calculator below can be found at
http://www.hamuniverse.com/jpole.html

I don't have the exact specs of a B-17s rudder, but My C-172 was taller
than
5 ft

Enter The Operating Frequency
Freq MHz



A (Long section) dimension is: feet, inches, meters

B (Short section) dimension is: feet, inches, meters

C (Feed point) dimension is: feet, inches, meters

D (Spacing) dimension is: feet, inches,
meters

Inside (spacing) dimensions are metal to metal measurements, NOT center to

Begin signatu My Spam filter looks for exclamation points, dollar
signs,
and other characters not used in general conversation. To reply, cleanse
your message of all emotion.
"Jim Weir" wrote in message
...
Did you really read what the guy had to say? Do you know that a j-pole
at
121.5
is longer than a B-17's rudder assembly? Do you understand that you
have
to
radiate equally efficiently at both the fundamental and second (NOT
third)
harmonic?

Did you read that he has only a small amount of fiberglass in the tail,
and that
most of it is carbon fiber? Did you read that there is another com
antenna in
that same location?

I read it and concluded that they guy didn't have a chance in hell of
putting
his ELT antenna in the tailfeathers, but waited around to see if
somebody
that
knew what they were talking about came up with a clever idea...I don't
claim to
have cornered the market on clever.

Do you understand that a j-pole does NOT have a built-in ground plane,
but
is a
matched half wave radiator? Why do you limit the dipole to a 90 degree
angle?
If SWR is all you are concerned with, I can give you an antenna that is
good
from DC to 20 GHz.. It is called a 51 ohm resistor.

Jim (still waiting for clever) Weir



shared these priceless pearls of wisdom:

-A j-pole antenna has a built in ground plane and works very well. Just
-google on jpole or j-pole antenna. Or maybe a full wave loop if you
-have the area for one. A dipole also can be used with up to a 90
degree
-angle in the center. Just some ideas. Contact a local ham radio club.
A
-dipole with a 90 degree angle is fairly omni-directional and easy to
-build.
-
-Have the antenna checked BEFORE testing for SWR with an MFJ antenna
-analyzer from a local ham club. The ARRL antenna handook for VHF is an
-excellent resource.
-
-I would definitely MAKE SURE the antenna cannot come loose. Use 50 ohm
-coax to feed if that is what impedence the radio expects.
-
-Rob


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com